a is obtuse such that sina=1/5 find the exact value of cosa

I did c^2+s^2=1

and cosa = =+/-(24^0.5)/5

but the aswer is just the negative root,,,is this always the case when obtuse simply or is this answer wrong?

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- May 14th 2008, 02:59 PMi_zz_y_illobtuse basic trig -ve solution
a is obtuse such that sina=1/5 find the exact value of cosa

I did c^2+s^2=1

and cosa = =+/-(24^0.5)/5

but the aswer is just the negative root,,,is this always the case when obtuse simply or is this answer wrong? - May 14th 2008, 03:20 PMPlato